U.S. patent application number 12/651929 was filed with the patent office on 2010-04-29 for method of monitoring intraocular pressure and treating an ocular disorder.
This patent application is currently assigned to GLAUKOS CORPORATION. Invention is credited to Morteza Gharib, David S. Haffner, Hosheng Tu.
Application Number | 20100106073 12/651929 |
Document ID | / |
Family ID | 36119418 |
Filed Date | 2010-04-29 |
United States Patent
Application |
20100106073 |
Kind Code |
A1 |
Haffner; David S. ; et
al. |
April 29, 2010 |
METHOD OF MONITORING INTRAOCULAR PRESSURE AND TREATING AN OCULAR
DISORDER
Abstract
The invention discloses a trabecular stent and methods for
treating glaucoma. The stent may incorporate an intraocular
pressure sensor comprising a compressible element that is implanted
inside an anterior chamber of an eye, wherein at least one external
dimension of the element correlates with intraocular pressure. In
some embodiments, the sensor may be coupled to the stent. Also
disclosed are methods of delivery of the stent and the sensor to
the eye.
Inventors: |
Haffner; David S.; (Mission
Viejo, CA) ; Tu; Hosheng; (Newport Coast, CA)
; Gharib; Morteza; (San Marino, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Assignee: |
GLAUKOS CORPORATION
Laguna Hills
CA
|
Family ID: |
36119418 |
Appl. No.: |
12/651929 |
Filed: |
January 4, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10950175 |
Sep 24, 2004 |
7678065 |
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12651929 |
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10626181 |
Jul 24, 2003 |
6981958 |
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10950175 |
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09847523 |
May 2, 2001 |
6666841 |
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10626181 |
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60505680 |
Sep 24, 2003 |
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Current U.S.
Class: |
604/8 ; 600/398;
604/19 |
Current CPC
Class: |
A61F 9/00781 20130101;
A61B 3/16 20130101 |
Class at
Publication: |
604/8 ; 600/398;
604/19 |
International
Class: |
A61M 5/00 20060101
A61M005/00; A61B 3/16 20060101 A61B003/16; A61M 1/00 20060101
A61M001/00 |
Claims
1. A method of monitoring intraocular pressure, comprising:
providing a delivery device having a size of at least 20 gauge, the
delivery device including a lumen extending through at least a
portion thereof; providing a sensor element configured to measure
intraocular pressure and being held in the lumen of the delivery
device; forming an incision in a cornea of an eye proximate a
limbal area of the eye; inserting the delivery device through the
incision into an anterior chamber of the eye; advancing the sensor
element, using the delivery device, from within the anterior
chamber to eye tissue; anchoring the sensor element to the eye
tissue to measure the intraocular pressure of the eye with the
sensor element being positioned completely within the anterior
chamber and being exposed to aqueous humor; and exposing the
anterior chamber to a drug.
2. The method of claim 1 additionally comprising providing an
implant held within the lumen of the delivery device.
3. The method of claim 2 additionally comprising positioning at
least a portion of the implant in ocular tissue using the delivery
device.
4. The method of claim 2 additionally comprising serially
delivering the sensor element and the implant into the eye.
5. The method of claim 1, wherein anchoring the sensor element to
the eye tissue comprises anchoring the sensor element to an iris of
the eye.
6. The method of claim 1, wherein providing a delivery device
having a size of at least 20 gauge comprises providing the delivery
device with a size in the range from about 20 gauge to about 40
gauge.
7. The method of claim 1, wherein forming an incision comprises
forming the incision with a sufficiently small size such that the
incision is self-sealing.
8. The method of claim 1 additionally comprising positioning an
implant within the eye.
9. The method of claim 8, wherein exposing the anterior chamber to
a drug comprises eluting the drug from the implant.
10. The method of claim 8 additionally comprising providing the
implant with a first portion and a second portion that is appended
from the first portion, wherein the first portion includes a lumen
and the second portion carries the drug.
11. The method of claim 8 additionally comprising providing the
drug as a coating on at least a portion of the implant.
12. The method of claim 8 additionally comprising providing the
drug as a coating on a biocompatible body of the implant.
13. The method of claim 8 additionally comprising providing the
delivery device with at least one of the sensor element and the
implant pre-loaded therein.
14. The method of claim 8 additionally comprising inserting the
implant through the incision in the eye.
15. The method of claim 8 additionally comprising positioning the
implant and the sensor element substantially simultaneously.
16. The method of claim 8 additionally comprising providing the
sensor element in or on the implant.
17. The method of claim 8, wherein positioning an implant comprises
positioning the implant in the eye such that a distal end portion
of the implant extends through ocular tissue and a proximal end
portion of the implant is disposed within the anterior chamber.
18. The method of claim 8 additionally comprising conducting
aqueous humor through the implant from the anterior chamber to a
physiologic outflow pathway of the eye.
19. The method of claim 8 positioning an implant comprises
positioning the implant in the eye such that a distal end portion
of the implant is disposed in a physiologic outflow pathway of the
eye and a proximal end portion of the implant is disposed within
the anterior chamber.
20. The method of claim 19 additionally comprising positioning the
distal end portion of the implant in Schlemm's canal.
Description
RELATED APPLICATIONS
[0001] The present application is a divisional application of U.S.
patent application Ser. No. 10/950,175, filed Sep. 24, 2004,
entitled "Implant with Intraocular Pressure Sensor for Glaucoma
Treatment," which is a continuation-in-part application of U.S.
patent application Ser. No. 10/626,181, filed Jul. 24, 2003,
entitled "Implant with Pressure Sensor for Glaucoma Treatment," now
U.S. Pat. No. 6,981,958, which is a continuation application of
U.S. patent application Ser. No. 09/847,523, filed May 2, 2001,
entitled "Bifurcatable Trabecular Shunt for Glaucoma Treatment,"
now U.S. Pat. No. 6,666,841. The parent U.S. patent application
Ser. No. 10/950,175, filed Sep. 24, 2004 also claims benefit from
U.S. Provisional Application No. 60/505,680 filed Sep. 24, 2003,
entitled "Intraocular Pressure Sensor." The present application
claims priority to each of these applications and the entireties of
each of these priority applications are hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] The present invention generally relates to medical devices
and methods for reducing intraocular pressure in the animal eye.
More particularly, the present invention relates to the treatment
of glaucoma by permitting aqueous humor to flow out of the anterior
chamber through a surgically implanted pathway.
[0003] The human eye is a specialized sensory organ capable of
light reception and able to receive visual images. The trabecular
meshwork serves as a drainage channel and is located in the
anterior chamber angle formed between the iris and the cornea. The
trabecular meshwork maintains a balanced pressure in the anterior
chamber of the eye by draining aqueous humor from the anterior
chamber.
[0004] About two percent of people in the United States have
glaucoma. Glaucoma is a group of eye diseases encompassing a broad
spectrum of clinical presentations, etiologies, and treatment
modalities. Glaucoma causes pathological changes in the optic
nerve, visible on the optic disk, and it causes corresponding
visual field loss, resulting in blindness if untreated. Lowering
intraocular pressure is the major treatment goal in all
glaucomas.
[0005] In glaucomas associated with an elevation in eye pressure
(intraocular hypertension), the source of resistance to outflow is
mainly in the trabecular meshwork. The tissue of the trabecular
meshwork allows the aqueous humor ("aqueous") to enter Schlemm's
canal, which then empties into aqueous collector channels in the
posterior wall of Schlemm's canal and then into aqueous veins,
which form the episcleral venous system. Aqueous is a transparent
liquid that fills the region between the cornea, at the front of
the eye, and the lens. The aqueous is continuously secreted by the
ciliary body around the lens, so there is a constant flow of
aqueous from the ciliary body to the eye's front chamber. The eye's
pressure is determined by a balance between the production of
aqueous and its exit through the trabecular meshwork (major route)
or uveal scleral outflow (minor route). The trabecular meshwork is
located between the outer rim of the iris and the back of the
cornea, in the anterior chamber angle. The portion of the
trabecular meshwork adjacent to Schlemm's canal (the
juxtacanilicular meshwork) causes most of the resistance to aqueous
outflow.
[0006] Glaucoma is grossly classified into two categories:
closed-angle glaucoma, also known as angle closure glaucoma, and
open-angle glaucoma. Closed-angle glaucoma is caused by closure of
the anterior chamber angle by contact between the iris and the
inner surface of the trabecular meshwork. Closure of this
anatomical angle prevents normal drainage of aqueous from the
anterior chamber of the eye. Open-angle glaucoma is any glaucoma in
which the angle of the anterior chamber remains open, but the exit
of aqueous through the trabecular meshwork is diminished. The exact
cause for diminished filtration is unknown for most cases of
open-angle glaucoma. Primary open-angle glaucoma is the most common
of the glaucomas, and it is often asymptomatic in the early to
moderately advanced stage. Patients may suffer substantial,
irreversible vision loss prior to diagnosis and treatment. However,
there are secondary open-angle glaucomas which may include edema or
swelling of the trabecular spaces (e.g., from corticosteroid use),
abnormal pigment dispersion, or diseases such as hyperthyroidism
that produce vascular congestion.
[0007] All current therapies for glaucoma are directed at
decreasing intraocular pressure. Medical therapy includes topical
ophthalmic drops or oral medications that reduce the production or
increase the outflow of aqueous. However, these drug therapies for
glaucoma are sometimes associated with significant side effects,
such as headache, blurred vision, allergic reactions, death from
cardiopulmonary complications, and potential interactions with
other drugs. When drug therapy fails, surgical therapy is used.
Surgical therapy for open-angle glaucoma consists of laser
trabeculoplasty, trabeculectomy, and implantation of aqueous shunts
after failure of trabeculectomy or if trabeculectomy is unlikely to
succeed. Trabeculectomy is a major surgery that is widely used and
is augmented with topically applied anticancer drugs, such as
5-flurouracil or mitomycin-C to decrease scarring and increase the
likelihood of surgical success.
[0008] Approximately 100,000 trabeculectomies are performed on
Medicare-age patients per year in the United States. This number
would likely increase if the morbidity associated with
trabeculectomy could be decreased. The current morbidity associated
with trabeculectomy consists of failure (10-15%); infection (a life
long risk of 2-5%); choroidal hemorrhage, a severe internal
hemorrhage from low intraocular pressure, resulting in visual loss
(1%); cataract formation; and hypotony maculopathy (potentially
reversible visual loss from low intraocular pressure).
[0009] For these reasons, surgeons have tried for decades to
develop a workable surgery for the trabecular meshwork.
[0010] The surgical techniques that have been tried and practiced
are goniotomy/trabeculotomy and other mechanical disruptions of the
trabecular meshwork, such as trabeculopuncture, goniophotoablation,
laser trabecular ablation, and goniocurretage. These are all major
operations and are briefly described below.
[0011] Goniotomy/Trabeculotomy: Goniotomy and trabeculotomy are
simple and directed techniques of microsurgical dissection with
mechanical disruption of the trabecular meshwork. These initially
had early favorable responses in the treatment of open-angle
glaucoma. However, long-term review of surgical results showed only
limited success in adults. In retrospect, these procedures probably
failed due to cellular repair and fibrosis mechanisms and a process
of "filling in." Filling in is a detrimental effect of collapsing
and closing in of the created opening in the trabecular meshwork.
Once the created openings close, the pressure builds back up and
the surgery fails.
[0012] Trabeculopuncture: Q-switched Neodymiun (Nd) YAG lasers also
have been investigated as an optically invasive technique for
creating full-thickness holes in trabecular meshwork. However, the
relatively small hole created by this trabeculopuncture technique
exhibits a filling in effect and fails.
[0013] Goniophotoablation/Laser Trabecular Ablation:
Goniophotoablation is disclosed by Berlin in U.S. Pat. No.
4,846,172 and involves the use of an excimer laser to treat
glaucoma by ablating the trabecular meshwork. This was demonstrated
not to succeed by clinical trial. Hill et al. used an Erbium:YAG
laser to create full-thickness holes through trabecular meshwork
(Hill et al., Lasers in Surgery and Medicine 11:341-346, 1991).
This technique was investigated in a primate model and a limited
human clinical trial at the University of California, Irvine.
Although morbidity was zero in both trials, success rates did not
warrant further human trials. Failure was again from filling in of
surgically created defects in the trabecular meshwork by repair
mechanisms. Neither of these is a viable surgical technique for the
treatment of glaucoma.
[0014] Goniocurretage: This is an ab interno (from the inside),
mechanically disruptive technique that uses an instrument similar
to a cyclodialysis spatula with a microcurrette at the tip. Initial
results were similar to trabeculotomy: it failed due to repair
mechanisms and a process of filling in.
[0015] Although trabeculectomy is the most commonly performed
filtering surgery, viscocanulostomy (VC) and non penetrating
trabeculectomy (NPT) are two new variations of filtering surgery.
These are ab externo (from the outside), major ocular procedures in
which Schlemm's canal is surgically exposed by making a large and
very deep scleral flap. In the VC procedure, Schlemm's canal is
cannulated and viscoelastic substance injected (which dilates
Schlemm's canal and the aqueous collector channels). In the NPT
procedure, the inner wall of Schlemm's canal is stripped off after
surgically exposing the canal.
[0016] Trabeculectomy, VC, and NPT involve the formation of an
opening or hole under the conjunctiva and scleral flap into the
anterior chamber, such that aqueous is drained onto the surface of
the eye or into the tissues located within the lateral wall of the
eye. These surgical operations are major procedures with
significant ocular morbidity. When trabeculectomy, VC, and NPT are
thought to have a low chance for success, a number of implantable
drainage devices have been used to ensure that the desired
filtration and outflow of aqueous through the surgical opening will
continue. The risk of placing a glaucoma drainage device also
includes hemorrhage, infection, and diplopia (double vision).
[0017] Examples of implantable shunts and surgical methods for
maintaining an opening for the release of aqueous from the anterior
chamber of the eye to the sclera or space beneath the conjunctiva
have been disclosed in, for example, U.S. Pat. Nos. 6,059,772 to
Hsia et al. and 6,050,970 to Baerveldt.
[0018] All of the above embodiments and variations thereof have
numerous disadvantages and moderate success rates. They involve
substantial trauma to the eye and require great surgical skill in
creating a hole through the full thickness of the sclera into the
subconjunctival space. The procedures are generally performed in an
operating room and have a prolonged recovery time for vision.
[0019] The complications of existing filtration surgery have
inspired ophthalmic surgeons to find other approaches to lowering
intraocular pressure.
[0020] The trabecular meshwork and juxtacanilicular tissue together
provide the majority of resistance to the outflow of aqueous and,
as such, are logical targets for surgical removal in the treatment
of open-angle glaucoma. In addition, minimal amounts of tissue are
altered and existing physiologic outflow pathways are utilized.
[0021] As reported in Arch. Ophthalm. (2000) 118:412, glaucoma
remains a leading cause of blindness, and filtration surgery
remains an effective, important option in controlling the disease.
However, modifying existing filtering surgery techniques in any
profound way to increase their effectiveness appears to have
reached a dead end. The article further states that the time has
come to search for new surgical approaches that may provide better
and safer care for patients with glaucoma.
SUMMARY OF THE INVENTION
[0022] There is a great clinical need for the treatment of glaucoma
by a method that is faster, safer, and less expensive than
currently available modalities, and by implanting a device having
pressure sensing capability for transporting aqueous from the
anterior chamber to Schlemm's canal.
[0023] Glaucoma surgical morbidity would greatly decrease if one
were to bypass the focal resistance to outflow of aqueous only at
the point of resistance, and to utilize remaining, healthy aqueous
outflow mechanisms. This is in part because episcleral aqueous
humor exerts a backpressure that prevents intraocular pressure from
going too low, and one could thereby avoid hypotony. Thus, such a
surgery would virtually eliminate the risk of hypotony-related
maculopathy and choroidal hemorrhage. Furthermore, visual recovery
would be very rapid, and the risk of infection would be very small,
reflecting a reduction in incidence from 2-5% to about 0.05%.
[0024] Techniques performed in accordance with embodiments herein
may be referred to generally as "trabecular bypass surgery."
Advantages of the present invention include lowering intraocular
pressure in a manner which is simple, effective, disease
site-specific, and can potentially be performed on an outpatient
basis.
[0025] In accordance with one embodiment, trabecular bypass surgery
(TBS) creates an opening, a slit, or a hole through trabecular
meshwork with minor microsurgery. TBS has the advantage of a much
lower risk of choroidal hemorrhage and infection than prior
techniques, and it uses existing physiologic outflow mechanisms. In
some aspects, this surgery can potentially be performed under
topical or local anesthesia on an outpatient basis with rapid
visual recovery. To prevent "filling in" of the hole, a
biocompatible elongated device is placed within the hole and serves
as a stent. U.S. Pat. No. 6,638,239, the entire contents of which
are incorporated herein by reference, discloses trabecular bypass
surgery.
[0026] In accordance with one embodiment, a trabecular shunt for
transporting aqueous humor is provided. The trabecular shunt
includes a hollow, elongate tubular element, having an inlet
section and an outlet section. In one embodiment, the outlet
section includes two bifurcatable segments or elements, adapted to
be positioned and stabilized inside Schlemm's canal. In another
embodiment, the outlet section is an axially linear section prior
to and during implantation, and becomes two bifurcated segments
after implantation.
[0027] In one embodiment, the trabecular shunt is placed inside a
delivery apparatus. When the trabecular shunt is deployed from the
delivery apparatus into the eye, the two bifurcatable elements of
the outlet section bifurcate in substantially opposite directions.
In one embodiment, a deployment mechanism within the delivery
apparatus includes a push-pull type plunger.
[0028] In another embodiment, a delivery applicator may be placed
inside a lumen of the hollow, elongate tube of the trabecular
shunt. The delivery applicator may include a deployment mechanism
for causing the two bifurcatable elements of the outlet section to
bifurcate. In some embodiments, the delivery applicator may be a
guidewire, an expandable basket, an inflatable balloon, or the
like.
[0029] In accordance with another embodiment, at least one of the
two bifurcatable elements is made of a shape-memory material, such
as Nitinol or a shape-memory plastic. The shape-memory material has
a preshape and a shape-transition temperature, such that the
shape-memory trabecular shunt bifurcates to its preshape when it is
heated to above the shape-transition temperature. The preshape of
the two bifurcatable elements material may be at an angle with
respect to the inlet section, preferably between about 70 degrees
and about 110 degrees. An external heat source may be provided,
which is adapted for heating the shape-memory material to above the
shape-transition temperature of the shape-memory material.
[0030] In some embodiments, the trabecular shunt may be made of one
or more of the following materials: polyvinyl alcohol, polyvinyl
pyrolidone, collagen, heparinized collagen,
polytetrafluoroethylene, expanded polytetrafluoroethylene,
fluorinated polymer, fluorinated elastomer, flexible fused silica,
polyolefin, polyester, polyimide, polysilison, silicone,
polyurethane, Nylon.TM., polypropylene, hydroxyapetite, precious
metal, Nitinol, stainless steel, biodegradable materials, and
biocompatible materials. Further, the outlet section of the
trabecular shunt may be configured as a coil, mesh, spiral, or
other appropriate configuration as will be apparent to those of
skill in the art. Further, the outlet section of the trabecular
shunt may be porous, semi-permeable, fishbone, and/or of a
continuous, solid form. The outlet section of the trabecular shunt
may have a cross-sectional shape that is elliptical (e.g., oval),
round, circular, D-shape, semi-circular, or irregular
(asymmetrical) shape.
[0031] In one embodiment, at least one of the two bifurcatable
elements has a tapered distal end, adapted for insertion ease. The
trabecular shunt may have its surface coated with a coating
material selected from one or more of the following:
polytetrafluoroethylene (e.g., Teflon.TM.), polyimide, hydrogel,
heparin, hydrophilic compound, anti-angiogenic factor,
anti-proliferative factor, therapeutic drugs, and the like. The
surface coating material may also provide a mechanism for
site-specific therapies.
[0032] In one embodiment, the device of the invention may include a
flow-restricting member for restricting at least one component in
fluid. The flow-restricting member may be a filter comprising one
or more filtration materials selected from the following: expanded
polytetrafluoroethylene, cellulose, ceramic, glass, Nylon, plastic,
fluorinated material, or the like. The flow-restricting member may
advantageously be a filter selected from the following group of
filter types: hydrophobic, hydrophilic, membrane, microporous, and
non-woven. The flow-restricting member acts to limit or prevent the
reflux of any undesired component or contaminant of blood, such as
red blood cells or serum protein, from the aqueous veins into the
anterior chamber. It is useful to restrict one or more of the
following components or contaminants: platelets, red blood cells,
white blood cells, viruses, bacteria, antigens, and toxins.
[0033] In some embodiments, the trabecular shunt may include a
pressure sensor for measuring the pressure of the anterior chamber
of an eye of a patient. The pressure sensor may further include an
electromagnetic (e.g., radiofrequency) transmitter, for wirelessly
transmitting pressure measurements to a pressure receiver outside
the patient's body.
[0034] Some embodiments relate to an apparatus for measuring
intraocular pressure. The apparatus may comprise a compressible
chamber sized to be placed in the anterior chamber of an eye. The
chamber may be configured to change in at least a first dimension
in response to a change in intraocular pressure such that the
change in the first dimension is indicative of the change in
intraocular pressure. In some embodiments, a second dimension of
the compressible chamber remains substantially constant during the
change in intraocular pressure.
[0035] Some embodiments relate to a method of measuring intraocular
pressure, the method comprising measuring a dimension of a
compressible chamber located in the anterior chamber of an eye, the
chamber configured to change in the dimension in response to a
change in intraocular pressure.
[0036] Some embodiments relate to a method of monitoring
intraocular pressure, the method comprising placing a compressible
chamber into the anterior chamber of an eye, the chamber configured
to change in at least one dimension in response to a change in
intraocular pressure. Some embodiments further comprise measuring
the at least one dimension to determine intraocular pressure.
[0037] Some embodiments relate to an intraocular pressure sensor
comprising a compressible element that is implanted inside an
anterior chamber of an eye, wherein at least one external dimension
of the element is correlated to compressing pressure reading. The
compressible element is anchored to a tissue of the eye, preferably
to an iris of the eye, wherein the element is positioned without
obstruction of vision.
[0038] In one embodiment, the element further comprises an interior
enclosure filled with a compressible fluid, wherein the
compressible fluid is a gas. In another embodiment, the
compressible element comprises a shape of a sphere, an ellipsoid
shape, a torus shape or other convenient shape. In still another
embodiment, at least a portion of the surface of the compressible
element is rendered radiopaque.
[0039] Some embodiments relate to an intraocular pressure sensor
comprising an implanted compressible element having at least one
external dimension and an external measuring means for remotely
viewing and measuring the at least one external dimension of the
element. In one embodiment, the external measuring means is a slit
lamp, an ultrasound imaging apparatus, a laser light apparatus, or
the like. In an alternate embodiment, the intraocular pressure
sensor comprises an implanted compressible element having at least
one external dimension and a measuring means for viewing and
measuring the at least one external dimension of the element,
wherein the measuring means is implanted or is one component of an
implanted stent in an eye.
[0040] Some embodiments relate to a method for measuring an
intraocular pressure of an eye, comprising: providing a
compressible element that is implanted inside an anterior chamber
of the eye, wherein at least one external dimension of the element
is correlated to compressing pressure reading; implanting the
element inside the eye; using an external measuring means for
remotely viewing and measuring the at least one external dimension
of the element; and calculating the intraocular pressure of the eye
by correlating the measured external dimension to the compressing
pressure reading.
[0041] Some embodiments relate to a method of providing a sensor
and an implant in an eye for treatment and monitoring of glaucoma.
The method may comprise providing a delivery device, the delivery
device comprising at least one implant having an inlet and an
outlet section, the inlet section being in fluid communication with
the outlet section and configured to conduct fluid from the
anterior chamber of an eye to Schlemm's canal. The method may
further comprise positioning the at least one implant in the eye
such that the inlet section is in the anterior chamber of the eye
and the outlet section is in Schlemm's canal and positioning the
sensor in the eye to measure the intraocular pressure of the
eye.
[0042] Some embodiments relate to a trabecular stent system for
glaucoma treatment, the stent system comprising: an elongate
tubular implant extending between an anterior chamber and Schlemm's
canal for transporting fluid from said anterior chamber to said
Schlemm's canal of an eye; and an intraocular pressure sensor in
association with the implant, said sensor comprising a compressible
element, wherein at least one external dimension of the element is
correlated to compressing pressure reading.
[0043] In another embodiment of the system for treating glaucoma,
the system may comprise an implant that is configured such that, in
use, the implant conducts fluid from the anterior chamber of an eye
to the Schlemm's canal of the eye and a pressure sensor that is
configured to be wholly implanted in the eye.
[0044] In a further embodiment, the trabecular stent system further
comprises a signal transmitter, said transmitter transmitting a
sensed signal from said sensor indicative of the sensed pressure to
a receiver. In some embodiments, the receiver is located outside of
the eye or inside the eye. In some embodiments, the signal
comprises a radiofrequency signal.
[0045] Some embodiments relate to a system for treating glaucoma,
comprising: an intraocular pressure sensor, said sensor comprising
a compressible element, wherein at least one external dimension of
the element is correlated to compressing pressure reading; an
elongate tubular implant for transporting fluid between an anterior
chamber and Schlemm's canal; and a delivery applicator, said
intraocular pressure sensor and said implant being positioned
within said delivery applicator for delivering into the anterior
chamber for implantation.
[0046] Among the advantages of trabecular bypass surgery in
accordance with the invention is its simplicity. The microsurgery
may potentially be performed on an outpatient basis with rapid
visual recovery and greatly decreased morbidity. There is a lower
risk of infection and choroidal hemorrhage, and there is a faster
recovery, than with previous techniques.
[0047] Further features and advantages of the present invention
will become apparent to one of skill in the art in view of the
Detailed Description that follows, when considered together with
the attached drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] FIG. 1 is a sagittal sectional view of an eye.
[0049] FIG. 2 is a cross-sectional view of the anterior chamber of
an eye.
[0050] FIG. 3A is a side elevational view of a glaucoma device
according to the present invention.
[0051] FIG. 3B is an end cross-sectional view through plane 1-1 of
FIG. 3A.
[0052] FIG. 4A illustrates the trabecular shunt of FIG. 3A at a
semi-deployment state.
[0053] FIG. 4B is an end cross-sectional view of section 2-2 of
FIG. 4A.
[0054] FIG. 5A illustrates the trabecular shunt of FIG. 3A in a
deployed state.
[0055] FIG. 5B is an end cross-sectional view of the trabecular
shunt, section 3-3 of FIG. 5A.
[0056] FIG. 5C is an end cross-sectional view of a bifurcatable
segment, section 4-4 of FIG. 5A.
[0057] FIG. 6 is a side cross-sectional view of the trabecular
shunt.
[0058] FIG. 7A is a side cross-sectional view of an alternate
embodiment of the trabecular shunt.
[0059] FIG. 7B is a side cross-sectional view of the trabecular
shunt of FIG. 7A in a partially deployed state.
[0060] FIG. 7C is a side cross-sectional view of the trabecular
shunt and a passive IOP pressure sensor loaded in series in a
delivery device.
[0061] FIG. 8A is a perspective view of the trabecular shunt placed
inside Schlemm's canal.
[0062] FIG. 8B is a perspective view of the trabecular shunt
coupled to a passive IOP pressure sensor and placed inside
Schlemm's canal.
[0063] FIG. 9 is a close-up sectional view of the eye, showing the
anatomical diagram of trabecular meshwork and the anterior chamber
of the eye.
[0064] FIG. 10 shows one embodiment of a passive IOP pressure
sensor element.
[0065] FIG. 11 is a cross-sectional view, section 5-5 of FIG.
10.
[0066] FIG. 12 shows another embodiment of a passive IOP pressure
sensor element.
[0067] FIG. 13 shows a block diagram for a glaucoma treatment
system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0068] FIGS. 1 to 13 illustrate an apparatus for the treatment of
glaucoma by trabecular bypass surgery in accordance with the
present invention.
[0069] FIG. 1 is a sagittal sectional view of an eye 10, while FIG.
2 is a close-up view, showing the relative anatomical locations of
trabecular meshwork 21, the anterior chamber 20, and Schlemm's
canal 22. Thick collagenous tissue known as sclera 11 covers the
entire eye 10 except that portion covered by the cornea 12. The
cornea 12 is a thin transparent tissue that focuses and transmits
light into the eye and through the pupil 14, which is the circular
hole in the center of the iris 13 (colored portion of the eye). The
cornea 12 merges into the sclera 11 at a juncture referred to as
the limbus 15. The ciliary body 16 extends along the interior of
the sclera 11 and is coextensive with the choroid 17. The choroid
17 is a vascular layer of the eye 10, located between the sclera 11
and retina 18. The optic nerve 19 transmits visual information to
the brain and is the anatomic structure that is progressively
destroyed by glaucoma.
[0070] The anterior chamber 20 of the eye 10, which is bound
anteriorly by the cornea 12 and posteriorly by the iris 13 and lens
26, is filled with aqueous. Aqueous is produced primarily by the
ciliary body 16, then moves anteriorly through the pupil 14 and
reaches the anterior chamber angle 25, formed between the iris 13
and the cornea 12. In a normal eye, the aqueous is removed from the
anterior chamber 20 through the trabecular meshwork 21. Aqueous
passes through trabecular meshwork 21 into Schlemm's canal 22 and
thereafter through the aqueous veins 23, which merge with
blood-carrying veins and into systemic venous circulation.
Intraocular pressure is maintained by the intricate balance between
secretion and outflow of the aqueous in the manner described above.
Glaucoma is, in most cases, characterized by the excessive buildup
of aqueous in the anterior chamber 20, which leads to an increase
in intraocular pressure. Fluids are relatively incompressible, and
pressure is directed relatively equally throughout the eye.
[0071] As shown in FIG. 2, the trabecular meshwork 21 is adjacent a
small portion of the sclera 11. Traditional procedures that create
a hole or opening for implanting a device through the tissues of
the conjunctiva 24 and sclera 11 involve extensive surgery, as
compared to surgery for implanting a device which ultimately
resides entirely within the confines of the sclera 11 and cornea
12, as is performed in accordance with one aspect of the present
invention. In one embodiment, an outflow pathway is created that
may operate to facilitate the flow of aqueous through or beyond the
trabecular meshwork 21. A device 31 for establishing an outflow
pathway, positioned through the trabecular meshwork 21, is
illustrated in FIG. 8.
[0072] In one embodiment, a method of placing a trabecular shunt
into an opening through trabecular meshwork, the method comprises
advancing and positioning a trabecular shunt having two distal
bifurcatable elements through the opening. In a further embodiment,
a method of placing a trabecular shunt into an opening through
diseased trabecular meshwork for transporting aqueous humor at the
level of the trabecular meshwork and using an existing outflow
pathway, the method comprises advancing and positioning a
trabecular shunt having a pressure sensor for measuring the
pressure of the anterior chamber of the eye through the opening. In
one embodiment, the method may further comprise transmitting the
measured pressure to a pressure receiver outside the body of the
patient.
[0073] Abita et al. in U.S. Pat. No. 6,579,235, the entire contents
of which are incorporated herein by reference, disclose a device
and methods for measuring intraocular pressure of a patient
including a sensor and an instrument external to the patient to
determine the intraocular pressure.
[0074] Wolfgang et al. in U.S. Patent Application publication
2004/0116794, the entire contents of which are incorporated herein
by reference, disclose a wireless intraocular pressure sensor
device for detecting excessive intraocular pressure above a
predetermined threshold pressure.
[0075] In a co-pending application Ser. No. 10/636,797 filed Aug.
7, 2003, entitled "Implantable Ocular Pump to Reduce Intraocular
Pressure," the entire contents of which are incorporated herein by
reference, an implant and a pressure sensor feedback system for
regulating intraocular pressure of an eye is disclosed.
[0076] Montegrande et al. in U.S. Patent Application publication
2003/0225318, the entire contents of which are incorporated herein
by reference, disclose an intraocular pressure sensor for sensing
pressure within an eye and for generating a sensor signal
representative of the pressure.
[0077] Jeffries et al., U.S. Patent Application publication
2003/0078487, the entire contents of which are incorporated herein
by reference, disclose an intraocular pressure measuring system
that includes a pressure sensor and an external device that
wirelessly communicates with the pressure sensor.
[0078] FIG. 3A shows an embodiment of the trabecular shunt 31
constructed according to the principles of the invention. The
trabecular shunt may comprise a biocompatible material, such as
medical grade silicone, trade name Silastic.TM., available from Dow
Corning Corporation of Midland, Mich.; or polyurethane, trade name
Pellethane.TM., also available from Dow Corning Corporation. In
some embodiments, other biocompatible materials (biomaterials) may
be used, such as polyvinyl alcohol, polyvinyl pyrolidone, collagen,
heparinized collagen, polytetrafluoroethylene, expanded
polytetrafluoroethylene, fluorinated polymer, fluorinated
elastomer, flexible fused silica, polyolefin, polyester, polyimide,
polysilison, silicone, polyurethane, Nylon, polypropylene,
hydroxyapetite, precious metal, Nitinol, stainless steel, or any
mixture of these or other biocompatible materials. In a further
embodiment, the trabecular shunt may comprise a composite
biocompatible material, with a surface made of one or more of the
above-mentioned biomaterials, and the surface is coated by a
material selected from Teflon, polyimide, hydrogel, heparin,
hydrophilic compound, anti-angiogenic factor, anti-proliferative
factor, therapeutic drugs, and the like. Suitable anti-angiogenic
or anti-proliferative factors may be selected from, for example,
protamine, heparin, steroids, anti-invasive factor, retinoic acids
and derivatives thereof, and paclitaxel or its analogues or
derivatives thereof.
[0079] The trabecular shunt transports aqueous at the level of the
trabecular meshwork and partially uses existing the outflow pathway
for aqueous, i.e., utilizing the entire outflow pathway except for
the trabecular meshwork, which is bypassed by the trabecular shunt
31. In this manner, aqueous is transported into Schlemm's canal and
subsequently into the aqueous collectors and the aqueous veins so
that the intraocular pressure is properly maintained within a
therapeutic range.
[0080] In one embodiment, the trabecular shunt 31 comprises a
hollow, elongated tubular element having an inlet section 32 and an
outlet section 33, wherein the outlet section 33 may comprise two
bifurcatable elements 34, 35 that are adapted to be bifurcated,
positioned, and stabilized inside Schlemm's canal. The hollow
elongated tubular element may comprise at least one lumen 36 for
transporting aqueous from the anterior chamber 20 of an eye to the
Schlemm's canal 22. A "bifurcatable" segment is defined in the
present invention as a segment, or components thereof, that can
change direction away or evert from a reference axis. The
"bifurcating" operation may be achieved by mechanical forces and/or
through the shape-memory property of a material.
[0081] For stabilization purposes, the outer surface of the outlet
section 33 may comprise a stubbed surface, ribbed surface, a
surface with pillars, textured surface, or the like. The outer
surface of the trabecular shunt 31 is biocompatible and
tissue-compatible so that the interaction between the outer surface
of the shunt and the surrounding tissue of Schlemm's canal is
minimal, and inflammation is reduced. FIG. 3B shows an end
cross-sectional view of section 1-1 of FIG. 3A. Each bifurcatable
segment 34, 35 has its own end configuration. At least one of the
two bifurcatable elements has a tapered distal end adapted for
insertion ease. The two bifurcatable elements 34, 35 are secured to
the inlet section 32 at a joint 37. In an alternate embodiment, at
least a slit 38, or scalloping, within the two bifurcatable
elements 34, 35 may be located near the joint 37 for stress release
when the two bifurcatable elements are bifurcated in two
substantially opposite directions. Other stress-releasing
mechanisms may also be utilized so as to make the bifurcation
operation of the bifurcatable elements safe and effective. The
outlet section 33 of the trabecular shunt 31 may possess a
cross-sectional shape selected from the following: oval shape,
round shape, circular shape, D-shape, semi-circular shape,
irregular shape, or random shape.
[0082] In another embodiment, the trabecular shunt 31 may comprise
a flow-restricting element for restricting at least one component
in fluid, wherein the flow-restricting element may be a filter
selected from a group of filtration materials comprising expanded
polytetrafluoroethylene, cellulose, ceramic, glass, Nylon, plastic,
and fluorinated material. Furthermore, the flow-restricting element
may be a filter selected from a group of filter types comprising a
hydrophobic filter, hydrophilic filter, membrane filter,
microporous filter, non-woven filter, and the like. In accordance
with the present invention, components in blood that may be
restricted by the flow-restricting element can include the
following: platelet, red blood cell, white blood cell, virus,
antigen, serum protein, and toxin. The flow-restricting element may
also be in the form of, for example, a check valve, a slit valve, a
micropump, a semi-permeable membrane, and the like. The purpose of
the flow-restricting element is to keep an undesired foreign
material from back flowing into the anterior chamber.
[0083] FIG. 4A shows the trabecular shunt of FIG. 3A in a
semi-deployed state, while FIG. 4B shows an end cross-sectional
view of section 2-2 of FIG. 4A. In one embodiment for shunt
delivery, the trabecular shunt 31 is placed inside a hollow
delivery apparatus 45. A delivery apparatus 45 comprises a distal
end 47, wherein the two bifurcatable elements 34, 35 of the outlet
section are self-bifurcatable in substantially two opposite
directions when the trabecular shunt 31 is deployed out of the
delivery apparatus 45. The slit 38 at the two bifurcatable elements
34, 35 comprises the separating regions 43A and 43B. The delivery
apparatus 45 may comprise a deployment mechanism for deploying the
trabecular shunt out of the delivery apparatus. In one embodiment,
the deployment mechanism is a plunger. The delivery mechanism may
be located at the handle of the delivery apparatus for deploying
the trabecular shunt.
[0084] FIG. 5A shows the trabecular shunt of FIG. 3A at a deployed
state. As the plunger is continuously pushed ahead, and the distal
end 47 of the delivery apparatus 45 retreats, the two bifurcatable
elements 34, 35 continue to deploy in two substantially opposite
directions. This may be accomplished by precontracting the two
bifurcatable elements within the delivery apparatus before the
delivery state. When the distal end of the delivery apparatus
withdraws beyond the joint point 37 located between the inlet
section 32 and the outlet section, the two bifurcatable elements
are fully deployed with their separating regions 43A, 43B apart
from each other. The outlet section of the trabecular shunt may be
made of a material form selected from a group comprising coil form,
mesh form, spiral form, porous form, semi-permeable form, fishbone
form, continuous solid form, or any form that is effective and
appropriate to evert the bifurcatable elements to be at one or more
angles with respect to a reference axis of the inlet section.
[0085] FIG. 5B shows an end cross-sectional view of the trabecular
shunt, section 3-3 of FIG. 5A, while FIG. 5C shows an end
cross-sectional view of a bifurcatable segment, section 4-4 of FIG.
5A. The original outer contour of the trabecular shunt 31 is
illustrated by a dashed line 49 in FIG. 5B. The lumen 36 of the
hollow elongated tubular element is for aqueous to flow through the
trabecular shunt. The shape of the end cross-section 35 is to
provide a stenting capability when the elements are placed inside
Schlemm's canal. The semicircular end cross-section of the
bifurcatable elements 34, 35 allows aqueous to freely flow into
aqueous collector channels in the external wall of Schlemm's
canal.
[0086] FIG. 6 shows another preferred embodiment of the trabecular
shunt constructed according to the principles of the invention. A
delivery applicator 52 may be placed inside a lumen of the hollow
elongated tubular element, wherein the delivery applicator 52
comprises a deployment mechanism for effecting the two bifurcatable
elements 34, 35 of the outlet section to substantially two opposite
directions. The delivery applicator may be selected from a group
comprising a guidewire, an expandable basket, an inflatable
balloon, or other expanding mechanism. In one embodiment, a
delivery applicator 52 with an expandable basket comprises a
plurality of expandable members 54A, 54B, 54C, 54D that all
securely joined at a proximal joint 55A and at a distal joint point
55B. A distal end of a push-pull type wire 51 is also joined at the
distal joint point 55B. The proximal joint 55A is located at the
distal end of a compact guidewire 53 of the delivery applicator.
Therefore, by pulling the push-pull wire 51 of the delivery
applicator toward the operator, each of the expandable members 54A,
54B, 54C, 54D expand radially outwardly so as to effect the outward
pushing action for the bifurcatable elements 34, 35.
[0087] U.S. Pat. No. 6,077,298 and U.S. patent application Ser. No.
09/452,963, filed Dec. 2, 1999, the entire contents of which are
incorporated herein by reference, disclose a medical device made of
shape-memory Nitinol having a shape-transition temperature. The
shape-memory material may be used in the construction of a
trabecular shunt 31. In one embodiment, a trabecular shunt
comprises a hollow elongated tubular element having an inlet
section and an outlet section, wherein the outlet section comprises
two bifurcatable elements adapted to be positioned and stabilized
inside Schlemm's canal. At least one of the two bifurcatable
elements may be made of a shape-memory material such as
shape-memory Nitinol or shape-memory plastic material. In a
preferred embodiment, the shape-memory Nitinol has a preshape and a
shape-transition temperature, wherein the shape-memory Nitinol
bifurcates to its preshape when the shape-memory Nitinol is heated
to above the shape-transition temperature, the preshape of the
shape-memory Nitinol being at an angle with respect to the inlet
section.
[0088] The shape-transition temperature for the shape-memory
Nitinol is preferably between about 39.degree. C. and about
90.degree. C. The shape-transition temperature is more preferred
between about 39.degree. C. and 45.degree. C. so as to minimize
tissue damage. The angle between the inlet section and the outlet
section is preferably between about 70 degrees and about 110
degrees so as to conform to the counter of Schlemm's canal. An
external heat source may be provided and adapted for heating the
shape-memory Nitinol to above the shape-transition temperature of
the shape-memory Nitinol. Examples of such external heat sources
include a heating pad, a warm cloth, a bag of warm water, remotely
deliverable heat, electromagnetic field, and the like. In another
embodiment, the shape-memory Nitinol may be embedded within a
biocompatible material selected from, for example, silicone,
polyurethane, porous material, expanded polytetrafluoroethylene,
semi-permeable membrane, elastomer, and mixture of the
biocompatible material thereof. In general, the bifurcatable
elements are relatively flexible and soft so that they do not
impart undesired force or pressure onto the surrounding tissue
during and after the deployment state.
[0089] For illustration purposes, a fishbone type outlet section is
shown to render the bifurcatable elements flexible and soft during
the deployment state. FIG. 7A shows an embodiment of the trabecular
shunt constructed according to principles of the invention. The
trabecular shunt comprises a plurality of fishbones and their
intermediate spacing, such as the fishbones 61A, 61B with a spacing
62A and the fishbones 61C, 61D with a spacing 62B. A delivery
apparatus 45 may be used to deliver the self-bifurcatable elements
34, 35 having fishbones configuration.
[0090] FIG. 7B shows the trabecular shunt of FIG. 7A in a
semi-deployed state. As the distal end 47 of the delivery apparatus
45 is pulled away from the distal end 39 of the shunt 31, the
self-bifurcatable elements 34, 35 tend to deploy to two opposite
directions. In the meantime, the spacing 62B between the two
fishbones 61C and 61D starts to expand and enlarge so that minimal
stress is exerted on the deployed bifurcated portion of the
bifurcatable elements 34, 35.
[0091] The trabecular shunt of the present invention may have a
length between about 0.5 mm to over a few millimeters. The outside
diameter of the trabecular shunt may range from about 30 .mu.m to
about 500 .mu.m or more. The lumen diameter is preferably in the
range of about 20 .mu.m to about 150 .mu.m, or larger. The
trabecular shunt may have a plurality of lumens to facilitate
multiple-channel flow. The outlet section may be curved or angled
at an angle between about 30 degrees to about 150 degrees, and
preferably at about 70 degrees to about 110 degrees, with reference
to the inlet section 32.
[0092] FIG. 8A is a perspective view illustrating the device 31 of
the present invention positioned within the tissue of an eye 10. A
hole or opening is created through the diseased trabecular meshwork
21. The outlet section of the device 31 is inserted into the hole,
wherein the inlet section is exposed to the anterior chamber 20
while the outlet section is positioned at about an exterior surface
3 of the diseased trabecular meshwork 21. In a further embodiment,
the outlet section may enter into Schlemm's canal or other existing
outflow pathways. A device as shown in FIG. 3 may be successfully
used to maintain the opening through diseased trabecular
meshwork.
[0093] In one embodiment, means for forming a hole/opening in the
trabecular meshwork 21 may comprise using a microknife, a pointed
guidewire, a sharpened applicator, a screw shaped applicator, an
irrigating applicator, or a barbed applicator. Alternatively, the
trabecular meshwork may be dissected off with an instrument similar
to a retinal pick or microcurrette. The opening may alternately be
created by retrograde fiberoptic laser ablation.
[0094] In a preferred embodiment of the trabecular meshwork
surgery, the patient is placed in the supine position, prepped,
draped and anesthesia obtained. In one embodiment, a small
(generally less than 1-mm) self-sealing incision is made. Through
the cornea opposite the shunt placement site, an incision is made
in the trabecular meshwork with an irrigating knife. The shunt is
then advanced through the corneal incision across the anterior
chamber held in a delivery apparatus or delivery applicator under
gonioscopic (lens) or endoscopic guidance. The apparatus or
applicator is withdrawn from the patient and the surgery is
concluded. The delivery apparatus or applicator may be within a
size range of 20 to 40 gauge, and preferably about 30 gauge.
[0095] In a further alternate embodiment, a method for increasing
aqueous humor outflow in an eye of a patient to reduce intraocular
pressure therein may comprise the following: (a) creating an
opening in trabecular meshwork; (b) inserting a trabecular shunt
into the opening, wherein the trabecular shunt comprises a hollow
elongated tubular element having an inlet section and an outlet
section, and wherein the outlet section comprises two bifurcatable
elements adapted to be positioned and stabilized inside Schlemm's
canal; and (c) bifurcating the two bifurcatable elements to
substantially two opposite directions.
[0096] The method may further comprise placing the trabecular shunt
inside a delivery apparatus during a delivery state, wherein the
two bifurcatable elements are self-bifurcatable in two
substantially opposite directions when the trabecular shunt is
deployed from the delivery apparatus. The method may further
comprise placing a delivery applicator inside a lumen of a hollow
elongated tubular element, wherein the delivery applicator
comprises a deployment mechanism for causing the two bifurcatable
elements to move in two substantially opposite directions.
[0097] The method may further comprise measuring and transmitting
pressure of the anterior chamber of an eye, wherein the trabecular
shunt comprises a pressure sensor for measuring and transmitting
pressure. The means for measuring and transmitting pressure of an
anterior chamber of an eye to an external receiver may be
incorporated within a device that is placed inside the anterior
chamber for sensing and transmitting the intraocular pressure. Any
suitable micro pressure sensor or pressure sensor chip known to
those of skill in the art may be utilized.
[0098] As shown in FIG. 9, the trabecular meshwork 21 constitutes a
small portion of the sclera 11. It is understandable that creating
a hole or opening for implanting a device through the tissues of
the conjunctiva 24 and sclera 11 is relatively a major surgery as
compared to a surgery for implanting a device through the
trabecular meshwork 21. In one embodiment, a passive IOP sensor
element 71 is secured to an iris 13 with at least one anchoring
member 75 to prevent the element from randomly floating inside the
anterior chamber. The sensor element is typically positioned out of
the line of vision. In another embodiment, the IOP sensor element
71 may be coupled to the trabecular shunt 31, as shown in FIG. 8B.
This may permit implantation of both the trabecular shunt 31 and
the pressure sensor in a single procedure. The sensor may be
coupled by any means know by those of skill in the art. For
example, the sensor may be coupled to the trabecular shunt 31 by
adhesive, soldering, etc. In some embodiments, the sensor may be
integrally formed with the trabecular shunt 31.
[0099] FIG. 9 shows a trabecular stent system for glaucoma
treatment, the stent system comprising: an elongate tubular implant
31 extending between an anterior chamber 20 and Schlemm's canal 22
for transporting fluid from said anterior chamber to said Schlemm's
canal of an eye; and an intraocular pressure sensor 71 in
association with the implant 31, said sensor comprising a
compressible element, wherein at least one external dimension of
the element is correlated to compressing pressure reading. The
trabecular stent system further comprises a signal transmitter 74
(for example, a radiofrequency signal transmitter), said
transmitter transmitting a sensed signal from said sensor 71
indicative of the sensed pressure to a receiver. The receiver may
be located outside of the eye or inside the eye.
[0100] The IOP sensor element can comprise a biocompatible
material, such as a medical grade silicone, for example, the
material sold under the trademark Silastic.TM., which is available
from Dow Corning Corporation of Midland, Mich., or polyurethane,
which is sold under the trademark Pellethane.TM., which is also
available from Dow Corning Corporation. In an alternate embodiment,
at least a portion of the sensor element can comprise other
biocompatible materials (biomaterials), such as polyvinyl alcohol,
polyvinyl pyrolidone, collagen, heparinized collagen,
tetrafluoroethylene, fluorinated polymer, fluorinated elastomer,
flexible fused silica, polyolefin, polyester, polysilicon, mixture
of biocompatible materials, and the like. In a further alternate
embodiment, a composite biocompatible material by surface coating
the above-mentioned biomaterial can be used, wherein the coating
material may be selected from a group consisting of
polytetrafluoroethylene (PTFE), polyimide, hydrogel, heparin,
therapeutic drugs, and the like.
[0101] Some embodiments relate to an intraocular pressure sensor
comprising a compressible element that is implanted inside an
anterior chamber of an eye, wherein at least one external dimension
of the element is correlated to a compressing pressure reading, and
an external measuring means for remotely viewing and measuring the
at least one external dimension of the element. Some embodiments
provide a pressure sensor element 71 in response to a remote
sensing and measuring instrument for measuring the IOP indirectly.
In this embodiment, the sensor element does not need supplemental
energy or electromechanical means for powering the sensor element.
It is thus a passive IOP sensing device.
[0102] FIG. 10 shows one embodiment of a passive TOP pressure
sensor element 71, while FIG. 11 shows a cross-sectional view,
section 5-5 of FIG. 10. The passive pressure sensor element 71 may
be anchored or secured to a tissue of the eye. For example, the
pressure sensor element 71 may be anchored to the iris 13 of the
eye, as shown in FIG. 9. The element may be attached to a
trabecular stent implant, as shown in FIG. 8B. The sensor element
is sized, dimensioned and configured to be suitably implanted
inside the eye out of the line of vision and visible to the
external measuring means. Although FIG. 8B illustrates an
embodiment in which the pressure sensor element 71 is located
underneath (posterior to) the trabecular shunt 31, the pressure
sensor element 71 may be placed at any location on the shunt 31. In
one embodiment, the pressure sensor element 71 is located above the
trabecular shunt 31 to permit external observation of the shunt 31.
In one embodiment, the longest dimension of the element is less
than about 1 cm, preferably less than about 5 mm. In other
embodiments, however, the longest dimension of the element may be
greater than about 1 cm or less than about 5 mm. In one embodiment,
the sensor element is made of compressible membrane material that
will respond to varying pressures in the eye.
[0103] In one preferred embodiment, the IOP pressure sensor element
71 comprises an enclosure with compressible fluid (for example, a
gas) entrapped within the enclosure. The sensor element 71 has a
length D.sub.2, a width D.sub.1 and a depth D.sub.3 as shown in
FIGS. 10 and 11. In some embodiments, the sensor element 71 is
sized, constructed, and configured so the compressing pressure
affects the change of the width D.sub.1 (in the illustrated case,
D.sub.1 is equal to D.sub.2) while not appreciably affecting
dimension D.sub.3. The passive IOP sensor element 71 is
precalibrated to show a correlation of the width D.sub.1 or length
D.sub.2 as a function of the compressing pressure (designated as
P). In another embodiment, the IOP sensor element 71 is
precalibrated to provide a correlation of the width change
(designated as .DELTA.D.sub.1) as a function of the compressing
pressure change (designated as .DELTA.P).
[0104] In one embodiment, the edge portion 73 along the width
D.sub.1 is more pressure-sensitive than the central portion 72
along the width D.sub.1 enabling viewing the total width as a
function of compressing pressure by a physician. In this
embodiment, a greater pressure in the eye would result in a change
of length in the width D.sub.1 along the edge portion 73 of the
sensor 71 than the change of the central portion 72. In some
embodiments, the construction material at the edge portion can be
different from that at the central portion. In another embodiment,
the thickness at the edge portion 73 can be different from that at
the central portion 72. In a further embodiment, the shape and size
of the passive IOP sensor element 71 is suitably configured to
yield the precalibrated correlation of the dimensions of the sensor
71 as a function of the compressing pressure (designated as P).
Some embodiments relate to an IOP sensor element comprising a
compressible enclosure, wherein compressible gas is enclosed within
the enclosure, and wherein a dimension of the enclosure is
correlated with a compressing pressure.
[0105] A compressible element of the ellipsoid shape has a major
diameter D.sub.1 and a minor diameter D.sub.3 (similar to the one
shown in FIGS. 10 and 11 with D.sub.1=D.sub.2). Place the element
inside a compressing pressure chamber with a pressure reading. The
dimension D.sub.1 is read as a function of the compressing pressure
P as follows:
TABLE-US-00001 Compressing pressure, Reading # D.sub.1 length, mm
mmHg 1 5.0 10.0 2 4.9 11.5 3 4.8 13.2 4 4.7 15.2 5 4.6 17.7 6 4.5
20.7 7 4.4 24.4 8 4.2 39.4
[0106] FIG. 12 shows another embodiment of a passive IOP pressure
sensor element 76. In one embodiment, the IOP pressure sensor or
sensor element may have unilateral expansion or shrinkage of
primarily a single diameter that takes place with the sphere. In
another embodiment, two or more dimensions change in response to
external pressure fluctuations. In the ellipsoid enclosure, (such
as the one shown in FIGS. 10 and 11) both the major diameter
D.sub.1 and the minor diameter D.sub.3 may change in response to
external pressure fluctuations. Measuring pressure with the
ellipsoid involves taking a measurement, preferably, of the major
or greater diameter D.sub.1. The major diameter of the ellipsoid is
truly visible from any potential angle of projection by locating
the single farthest distance between opposing outer surfaces on the
ellipsoid on a line that passes through the center. The distance
thus measured is plotted onto a calibration curve showing the major
diameter vs. external pressure for the specific ellipsoid and the
corresponding pressure reading.
[0107] In a preferred embodiment, the IOP pressure sensor is
substantially a sphere in shape, rather than being elliptical. In
this spheroid embodiment (not shown), the dimensions D.sub.1,
D.sub.2, and D.sub.3 are substantially equal. This embodiment has
the advantage of compressing substantially equally in all or nearly
all dimensions in response to an increase in intraocular pressure,
so one may perhaps easily measure a diameter in order to obtain a
reading that correlates with IOP.
[0108] In the case of a compressible tubular wheel (such as a
torus) as shown in FIG. 12, the thickness 78, the outer diameter
79, and the inner diameter 77 change as a function of external
pressure. In one embodiment, the changes in the thickness, the
outer diameter and the inner diameter are relatively uniform,
wherein uniform changes in these dimensions assume that the bodies
are sized and constructed so that pressure changes affect uniform
and smooth dimensional changes in most or all dimensions. Measuring
pressure with the torus involves measuring the outer diameter 79.
The outer diameter of the torus is visible from any potential angle
of projection by locating the single farthest distance between the
opposing outer surfaces on the torus on a line that passes through
the center. The distance thus measured is plotted onto a
calibration curve showing the outer diameter vs. external pressure
for the specific torus and the corresponding pressure reading.
Alternately, the inner diameter can also be measured by viewing the
maximum dimension and ensuring that the outside diameter is not
mistakenly captured.
[0109] In one embodiment, the passive IOP sensor element is a
sphere, a spherical ball, an ellipsoid ball, a torus type spherical
tube or other dimensional element, preferably a nearly perfect
sphere, whose sphere diameter changes in all directions uniformly
with a change in external pressure. In a further embodiment, the
sphere could be situated and viewed from any angle. The sphere
could float in the eye, on a tether perhaps, and still be
accurately sensed without elaborate positioning requirements. The
spheres or element 71, 75 are biocompatible and suitable for
implantation in an eye.
[0110] In one embodiment, at least a part of the surface of the
enclosure is rendered radiopaque for X-ray visualization. In
another embodiment, at least a part of the surface of the enclosure
is colored or coated with a visualizable material for external
signal viewing. The external means for remotely viewing and
measuring the at least one external dimension of the element can be
a slit lamp, an ultrasound imaging apparatus, a laser light
apparatus, the X-ray imaging apparatus or the like. The enclosure
with enclosed gas is also visible by ultrasound.
[0111] FIG. 13 shows a block diagram for a glaucoma treatment
system of the present invention. Some aspects of the invention
relate to a system for treating glaucoma 81. The system may
comprise an intraocular pressure sensor 71 that comprises a
compressible element 86 with at least one external dimension of the
element is configured to be correlated to the compressing pressure
reading. The system may further comprise an elongate tubular
implant 31 for transporting fluid between an anterior chamber and
Schlemm's canal and a delivery applicator 82. The intraocular
pressure sensor and the implant may be positioned within said
delivery applicator for delivering into the anterior chamber for
implantation. In some embodiments, the intraocular pressure sensor
71 and the implant 31 may be serially contained in the delivery
applicator to permit application of the implant 31 and the sensor
71 in one procedure, as shown in FIG. 7C. This may permit
implantation of the implant 31 and the sensor 71 without the need
for discreet delivery applicators or incisions in the eye. The
operation of the delivery applicator may be the similar to that
described above with respect to the delivery applicator of the
implant 31 in FIGS. 6-7B.
[0112] Some aspects of the invention relate to a trabecular stent
system 83 for glaucoma treatment, the stent system may comprise an
elongate tubular implant that is configured to extend between an
anterior chamber and Schlemm's canal for transporting fluid from
said anterior chamber to said Schlemm's canal of an eye. The system
may also comprise an intraocular pressure sensor in association
with the implant, and the sensor may comprise a compressible
element that has at least one external dimension that is correlated
to compressing pressure reading (as shown in a relationship figure
in the block 86). The trabecular stent system may further comprise
a signal transmitter (such as a radiofrequency transmitter 74), and
the transmitter may transmit a sensed signal 84 from the sensor
indicative of the sensed pressure to a receiver 85. The receiver
may be located either outside of the eye or inside the eye.
[0113] In a co-pending application Ser. No. 10/910,962, filed Aug.
4, 2004, entitled "Implantable Ocular Pump to Reduce Intraocular
Pressure," the entire contents of which are incorporated herein by
reference, disclosed are energy sources for powering a micropump on
a trabecular stent. In a co-pending application Ser. No.
10/636,797, filed Aug. 7, 2003, entitled "Implantable Ocular Pump
to Reduce Intraocular Pressure," the entire contents of which are
incorporated herein by reference, disclosed is conversion of
mechanical stress, such as a group comprising blink pressure
pulses, ocular pressure pulses, body motion, head motions, and eye
motions, to piezoelectricity.
[0114] Some embodiments relate to a method for measuring an
intraocular pressure of an eye that may comprise the following: (a)
provide a compressible element that is implanted inside an anterior
chamber of the eye, wherein at least one external dimension of the
element is correlated to compressing pressure reading; (b)
implanting the element inside the eye; (c) using an external
measuring means for remotely viewing and measuring the at least one
external dimension of the element; and (d) calculating the
intraocular pressure of the eye by correlating the measured
external dimension to the compressing pressure reading.
[0115] From the foregoing description, it should be appreciated
that a novel approach for the surgical treatment of glaucoma has
been disclosed for reducing IOP and sensing and measuring IOP from
outside of the eye has been disclosed for measuring intraocular
pressure. While the invention has been described with reference to
specific embodiments, the description is illustrative of the
invention and is not to be construed as limiting the invention.
Various modifications and applications of the invention may occur
to those who are skilled in the art, without departing from the
true spirit or scope of the invention. The breadth and scope of the
invention should be defined only in accordance with the appended
claims and their equivalents.
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